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View Full Version : Pressure Reducer on Submersable pump?


tomcl
03-22-2006, 07:14 PM
Has anyone used pressure reducers on submersable pumps, or do you need a pressure tank--The pump puts out around 125psi?

Thanks for any help on this

Wet_Boots
03-22-2006, 09:01 PM
You need a pressure tank, even if it's a small one, and you're not supplying a house's water usage. You also need the data on the well installation, along with the make and model of the pump. If you have the performance curve of the pump, or can find it online, you can design a system to match the well-and-pump output.

brookviewlawncare
03-23-2006, 09:30 PM
why must he use i pressure tank if system design is correct for pump output why cant he just use a pump start ?

Wet_Boots
03-24-2006, 04:10 AM
Since pump output is on a curve, the OP's description of the pump's performance as "puts out around 125psi" suggests to me that the performance curve isn't known. At least not yet. I sure hope the pump isn't running at 125 psi with poly-pipe for the output. And, if I did have to operate with 125 psi from a well, I'd want the 'shock absorber' effect of a pressure tank, even if all I used was a tiny top-of-the-pump tank you sometimes see on shallow-well jet pumps. The use of a tank also dovetails neatly with a pressure switch.

The thinking here isn't "what do I need to make it operate" so much as "what do I need in case things malfunction" - a pressure relief valve could also be added to the arrangement, for an additional level of protection.

brookviewlawncare
03-24-2006, 08:26 PM
what would be the need for the pressure relif valve if he uses a tank and pressure switch? i agree about the 125 psi and the curve but you would have to be nuts to be design a system on that side of the pump curve

Wet_Boots
03-24-2006, 08:48 PM
I've never seen a pressure-switch-controlled submersible without one, since most of those multi-stage pumps can develop enough pressure to blow their poly drop pipes if they run into a closed valve. Come to think of it, I do remember a submersible pump installation that had no pressure relief valve. It so happened that the pressure switch did fail, and the pump had enough pressure to burst the poly main line of the old sprinkler system it supplied. To the homeowner's distress, the break was underneath the concrete deck of the swimming pool that was put in after the sprinkler system.

brookviewlawncare
03-24-2006, 10:05 PM
never new that I have never installed a pressure relif valve on any sub smaller than a 5hp

Critical Care
03-24-2006, 11:32 PM
How about using a cycle stop valve?

Wet_Boots
03-25-2006, 12:04 AM
I always thought that was a lazy-man's method, instead of matching system performance to water supply. With interchangeable rotor nozzles, the matching is pretty simple. Still, the device can have its uses.

Also, notice the presence of both pressure switch and pressure relief valve in the diagram. For all pumps, a pressure relief is cheap insurance, compared to what it protects.

PurpHaze
03-25-2006, 12:19 PM
For all pumps, a pressure relief is cheap insurance, compared to what it protects.

Reminds me of the time we were having problems with one of our BIG pumps at one of the high schools. We were standing in the area of the backflow off to the side of the pressure tank when I heard a rumbling sound. I backed up through the gate as the relief valve opened and dumped water all over two other guys. :laugh:

Critical Care
03-25-2006, 03:13 PM
With the Cycle Stop layout you could maintain 70 psi (adjustable) while running one zone, and as the zone would shutoff the cycle stop valve would begin to close with only several gpm to fill the pressure tank. If a second zone doesn’t come on, then the pressure would rise to the pressure switch shutoff setting… which in this case may be 75 psi, but if another zone does come on then the cycle stop valve opens back up and the pressure tank empties.

brookviewlawncare
03-25-2006, 05:45 PM
I agree about zone size to pump curve. cycle stop valve does have its placein a large pump station.If i look the diagram cs1v and csv1z do not have a pressure relief valve.

Wet_Boots
03-25-2006, 06:21 PM
Hopefully, no one will install a cycle stop valve in such a way that the extra pressure in the upstream side could cause a blowout. If I encounter a well, I match the system to the supply, and figure it's worth the effort, considering I'm charging for it.

YardPro
03-26-2006, 08:46 AM
the cycle stop valves are wonderful devices.
we use them all the time on our commercial properties. We do put in 2 80 gallon bladder tanks as well. We run 5hp submersibles that put out almost 75-100gpm.

you can run a hose bib from the 5hp pump without issues.

Critical Care
03-26-2006, 01:53 PM
YardPro, do you really need two 80 gallon bladder tanks? Cycle Stop shows an 86 gallon tank replacing a 10,000 gallon tank.

YardPro
03-26-2006, 02:01 PM
the problem with this system is that that there are small leaks somewhere in the irrigation runs.

we first installed only one tank, and the cycle times of the pupm were too short.
so instead of spending thousands running new mains, or looking for a few small leaks, the decided to bandaid the problem with two tanks. this extends the cycle times.

this particular property had a poorly installed system from the beginning, but will not shell out the cash for the redo....

Wet_Boots
03-26-2006, 03:18 PM
If i look the diagram cs1v and csv1z do not have a pressure relief valve. The pressure relief is item F in the lower diagrams. For a home submersible install, it's a less-than-ten-bucks no-brainer to thread a small relief valve into the pump tank tee.

I would sort of object to a five horse pump running constantly to push hose bib water, on the basis of wasted energy. Who knows, in future days, the 'smart pumps' may become standard issue, and no energy will have to be lost in a cycle stop valve.

Of course, for the crappy other-guy installs we do service on, it's whatever works. ;)

Critical Care
03-26-2006, 09:54 PM
I would sort of object to a five horse pump running constantly to push hose bib water, on the basis of wasted energy. Who knows, in future days, the 'smart pumps' may become standard issue, and no energy will have to be lost in a cycle stop valve.

Huh, what energy is lost through a cycle stop valve? Are you saying that you lose energy because it doesnít allow a pump to cycle on and off?

Isnít cycling a pump on and off not a good thing? Most motor and pump failures occur during start up, right? And restricting the output of a pump, five horse of whatever, doesnít mean that youíre wasting energy. To the contrary, back pressure pulls less amperage, uses less electricity, and the motor will run cooler. Of course, when there is no demand on even the cycle stop system the pump will shut down.

Perhaps the closest thing that weíll have to a smart pump is the variable frequency drive, or variable speed pump. But...for a hefty price tag, eh?

Wet_Boots
03-27-2006, 04:09 AM
Any pressure regulation is lost energy. When you pump your own water, the lost pressure through the system, cycle-stop-valve or no, represents energy you pay for. That's more 'ag thinking' than lawn sprinkler thinking, where operating costs are rarely considered.

Despite any 'tech info' you might read on the cyclestopvalves.com website, there is not an exact relation between water flow through a pump, and the electricity consumed by said pump. If a 5 hp submersible that could push 50 gpm gets choked down to 5 gpm by a cycle-stop-valve, you are not getting a 90 percent reduction in energy consumed by the pump.

A cycle-stop-valve does what it says. If your pump/tank(s) combination is capable of short-cycling, then the valve has a use. I remember some ancient subersible pump installation that had several very-large galvanized pressure tanks off in a separate room in the basement. No easy nozzle changeouts then, back in the days of brass impact heads. Near to a thousand gallons of water capacity. Take that, short-cycling!

YardPro
03-28-2006, 07:51 AM
boots

the hose is not constantly running with the well.

it is a boat wash down that is only used during the summer. Even then it in only used infrequently.

the proplem was that to hook it to city water they would have had to either cut up the parking lot or hand dug 600' down a 1' wide strip full of roots where all the utilities come in. boy that would required a lot of energy expendature.....

Wet_Boots
03-28-2006, 09:04 AM
It's only the short-cycling you have to worry about. A hose bib running from a 5 HP submersible shouldn't be able to draw down the pressure tank(s) in less than two minutes. Basically, in a proper submersible pump install, <u>nothing</u> should be able to draw down the pressure tank(s) in the minimum time period one designates between pump starts.

YardPro
03-28-2006, 09:12 PM
that's why we have the two tanks on our system
and you get two people using hoses from the bib and you are putting out 10gpm from the bib. this will easially deplete a pressure tank to the point where the pump kicks on.

it only takes about 1 minute to fill the tank, then another minute to kick it back on...